Classic to Touch UI Migration for AEM: Multifields

<%
...
boolean isComposite = cfg.get("composite", false);
//customizations
boolean isLegacy = MultifieldUtils.isLegacy(values);
boolean isEmpty = isEmpty(slingRequest, name, values);
String sourceProperty = cfg.get("sourceProperty", String.class);
...
 
%><coral-multifield <%= attrs.build() %>> <%
try {
    if(isLegacy){
           for (Object v : values) {
               %><coral-multifield-item><% include(field, MultifieldUtils.createValueMap(name, v.toString(), sourceProperty), cmp, slingRequest); %></coral-multifield-item><%
           }
       } else if (isComposite) {
           ...
   }
...
 
   <%!
...
 
private static boolean isEmpty(SlingHttpServletRequest slingRequest, String name, Object[] values) {
   Resource contentResource = getContentResource(slingRequest, name);
   if (contentResource != null && contentResource.hasChildren()) {
       return false;
   }
   if (values.length > 0) {
       return false;
   }
   return true;
}
%>

public class MultifieldUtils {
 
   private static final Logger LOG = LoggerFactory.getLogger(MultifieldUtils.class);
 
   private MultifieldUtils() {
   }
 
   /**
    * Retrieves a List of ValueMap objects representing the values of multifield items
    * works with both legacy (JSON) and new (node) formats
    *
    * @param resource  component resource
    * @param fieldName the name of a multifield's field
    * @return a list of ValueMap objects
    */
   public static List<ValueMap> getItems(Resource resource, String fieldName) {
       return getItems(resource, fieldName, null);
   }
 
   /**
    * Retrieves a List of ValueMap objects representing the values of multifield items
    * works with both legacy (JSON) and new (node) formats
    *
    * @param resource       component resource
    * @param fieldName      the name of a multifield's field
    * @param sourceProperty in case a custom ClassicUI field is transferred to a simple Coral3 multifield,
    *                       represents the name of the property from JSON to be mapped to the field in JCR
    * @return a list of ValueMap objects
    */
   public static List<ValueMap> getItems(Resource resource, String fieldName, String sourceProperty) {
       try {
           Resource multifieldNode = resource.getChild(fieldName);
           if (multifieldNode == null || ResourceUtil.isNonExistingResource(multifieldNode){
return Collections.emptyList(); //multifield is not configured
           }
 
           List<Resource> children = StreamSupport.stream(multifieldNode.getChildren().spliterator(), false).collect(Collectors.toList());
           if (!children.isEmpty()) { // multifield items saved as nodes
               return children.stream()
                       .map(Resource::getValueMap)
                       .collect(Collectors.toList());
           }
           Object[] multifieldValues = resource.getValueMap().get(fieldName, new Object[0]);
           if (isLegacy(multifieldValues)) { // legacy JSON format
               return Arrays.stream(multifieldValues)
                       .map(value -> createValueMap(fieldName, value.toString(), sourceProperty))
                       .collect(Collectors.toList());
           }
           return Arrays.stream(multifieldValues) // a simple array
                   .map(value -> createValueMap(fieldName, value))
                   .collect(Collectors.toList());
 
       } catch (Exception e) {
           LOG.error("Can't get items form field {}: {}", fieldName, e);
       }
 
       return Collections.emptyList();
   }
   /**
    * @param fieldValues an array representing the values of a multifield
    * @return true, if the field contains legacy (JSON) structure
    */
   public static boolean isLegacy(Object[] fieldValues) {
       return fieldValues.length > 0 && fieldValues[0].toString().trim().startsWith("{");
   }
   /**
    * @param name  field name
    * @param value field value
    * @return a single entry value map with the given name and value
    */
   public static ValueMap createValueMap(String name, Object value) {
       ValueMap map = new ValueMapDecorator(new HashMap<>());
       map.put(name, value);
 
       return map;
   }
   /**
    * Creates a value map from a JSON string
    *
    * @param fieldName      in case a customComplex field is transferred to a simple coral multifield,
    *                       represents the name of the field in JCR
    * @param jsonString     a JSON string representing a multifield item
    * @param sourceProperty (optional) in case a custom ClassicUI field is transferred to a simple Coral3 multifield,
    *                       represents the name of the property from JSON to be mapped to the field in JCR
    * @return a valueMap representing a multifield item
    */
   public static ValueMap createValueMap(String fieldName, String jsonString, String sourceProperty) {
       ValueMap map = new ValueMapDecorator(new HashMap<>());
 
       JsonObject itemJson = new JsonParser().parse(jsonString).getAsJsonObject();
       if (StringUtils.isNotBlank(sourceProperty)) {
           String sourceFieldValue = itemJson.get(sourceProperty).getAsString();
           map.put(fieldName, sourceFieldValue);
       } else {
           map.put(JcrConstants.JCR_PRIMARYTYPE, JcrConstants.NT_UNSTRUCTURED);
           itemJson.entrySet().forEach(entry -> map.put(entry.getKey(), entry.getValue().getAsString()));
       }
 
       return map;
   }
 
}